Hobbyists and others maintain aquariums for displaying fish and related aquatic life. Frequently a sandy bottom layer is provided for covering the floor of the receptacle. As a replacement for the sand layer it has been proposed in the past grind up waste material from the manufacture of polyester buttons for the purpose of providing a sort of granuled coating material for the bottoms of aquariums. Such material provides an opaque uniform coating layer that closely simulates the appearance of a sandy bottom and provides a useful outlet for an otherwise waste material.